The effects of impurity-free vacancy diffusion using a SiO2 capping layer on the optical and opto-electronic properties of the In0.53Ga0.47As/In0.52Al0.48As multiple quantum wells electro-absorption modulator structure were investigated. A significant improvement (about 20 times compared to an as-grown sample) of photoluminescence intensity was observed after thermal treatments at above 700C. In this structure, however, a red shift was observed after rapid thermal annealing using the SiO2 capping layer, in contrast to the blue shift in conventional interdiffused multi-quantum-well. A red shift of about 27meV was obtained by annealing at 800C for 45s without noticeable photoluminescence line-width broadening. It was believed that the red shift could be attributed to exchange between the Ga of an InGaAs well and the In of an InAlAs barrier.

Influence of Impurity-Free Vacancy Diffusion on the Optical and Opto-Electronic Properties of the In0.53Ga0.47As/In0.52Al0.48As Multiple Quantum Wells Electro-Absorption Modulator Structure. J.S.Yu, J.D.Song, Y.T.Lee, H.Lim: Semiconductor Science and Technology, 2005, 20[8], 851-5